Heat transfer device with condensate drainage means



y 1961 H. E. CASWELL 2,983,115

HEAT TRANSFER DEVICE WITH CONDENSATE DRAINAGE MEANS Filed Feb. 3, 1958 INVENTOR. Howard E. Coswell,

BY WM ATTORNEY United States, Patent Howard E. Caswell, East Syracuse, N.Y., assignor to Carrier Corporation, Syracuse, N.Y., a corporation of Delaware Filed Feb. 3, 1958, Ser. No. 712,843 1 Claim. (Cl. 62-285) This invention relates broadly to heat transfer devices.

More specifically, this invention relates to a heat transfer unit equipped with means for increasing its efliciency.

It is well known that when a heat transfer unit such as a heat transfer coil having a first medium flowing through a confined passage is used to lower the temperature of a medium flowing over the surface of the unit, that condensation of the medium fiowing over the surface of the coil impairs the efiiciency of the unit. It is therefore the principal object of this invention to provide a heat transfer coil with an arrangement for the purpose of expediting drainage of condensate from the surface of the coil to thereby increase the efficiency of the unit.

A further object of the invention is the provision of a heat transfer coil equipped with a trough arrangement for draining portions of the transfer coil and thereby preventing drainage, from one portion of the coil to a subsequent portion of the coil, of the condensate.

The purposes and objects of this invention are attained by providing a heat transfer coil having a series of successive parallel tubular paths with a trough attached to extended surface elements forming a part of the heat transfer unit, so that condensate formed on each successive run and its associated extended surface may be carried away without the possibility of condensate formed on one run of the coil draining to the succeeding run and thereby cause an insulating layer about the surface of the heat transfer tube.

Other objects and features of the invention will be apparent upon a consideration of the ensuing specification and drawings wherein:

Figure 1 is a partial side view of a heat transfer unit of the type contemplated by this invention;

Figure 2 is an enlarged view of a portion of the coil shown in Figure 1;

Figure 3 is a section taken through lines 33 on Figure 2 showing the arrangement forming the subject of this invention, and

Figure 4 is an exploded view of the coil and condensate drainage means illustrated in Figures 1, 2 and 3.

Referring more particularly to the drawings it will be noted that a heat transfer coil of the type contemplated by this invention is shown in Figure 1.

The coil includes a tubular member having a series of parallel linear portions 10, interconnected at adjacent ends by non-linear portions 11. The portions 10 and 11 of the coil form a serpentine path for the flow of a first fluid medium to be utilized in a heat transfer process. The serpentine coil is further provided with tube sheets 12, serving to support the coil for assembly in apparatus of which the coil is a component.

In the interests of obtaining efiiciency, the linear portions of the coil 10 are provided with extended surface elements 13. The particular form in which the extended surface elements are utilized is one primarily of choice. For the purpose of describing the invention, it has been decided to illustrate the extended surface as being formed from the material forming the tube wall. Finned tubing of this kind is formed by extruding portions of the tube wall between closely spaced forming elements.

As pointed out above, the heat transfer coil provides 2,983,115 Patented May 9, 1961 a confined path for the flow ofthe first fluid and further offers a surface over which a second medium in the gaseous state may flow. Normally the temperature differential existing between the two media is suflicient to cause condensation of the second medium as it flows over the coil. One of the problems inherent in equipment of this type involves the presence of the condensed medium upon the surfaces of the coil. It will be appreciated that the condensate acts as an insulating layer and thereby impairs subsequent heat transfer action. Normally the coil is used under circumstances where the condensation is free to flow by gravity to a common collecting means located below the lowermost run of the coil. Under these circumstances it will be appreciated that the effect of the condensate dripping over the surfaces of the coil is most detrimental to those tubes forming the bottom runs of the coil. To overcome the substantial losses involved by the presence of the condensate on the coil, each of the extended surface elements 13 has in its lower portion a notch 14.

Assembled within the aligned notches 14 is a troughlike element 15, substantially U-shaped when viewed in section. The function of the trough 15 which in the interest of preventing substantial pressure drop is disposed Wholly within the confines of the notch, is to receive and to provide a path for condensate drainage from each run of the tube, with which the particular element 15 is associated. To achieve this action the trough 15 is provided, within the notches 14 of the individual elements 13, with a pitch sufiicient to insure runoff of the condensate collected from a portion of the individual extended surface element as Well as the adjoining portion of the tube. This may be accomplished by either providing a slope to the tubes, or by varying the depth of the notch from fin to fin or by varying the depth of the trough. Other arrangements for providing this action may suggest themselves to those skilled in the art.

It will be understood that the structural details of the heat transfer coil exclusive of the condensate drain feature may be varied within the scope of the invention. The serpentine arrangement herein disclosed is selected for the purpose of illustrating the invention, it being understood that the invention may be applied to other forms of heat transfer devices without departing from the scope of the invention as set forth in the appended claim.

While I have described a preferred embodiment of my invention, it will be understood my invention is not limited thereto, since it may be otherwise embodied within the scope of the following claim.

I claim:

Heat transfer apparatus for exchanging heat between a first condensible gaseous medium and a second medium comprising conduit means forming a confined path for the flow of the second medium, extended surface means associated with said first means and forming therewith a condensate collection surface subject to flow of gaseous medium thereover, said extended surface means being provided with notches arranged in a predetermined pattern and a trough assembled within a portion of the extended surface means defining each notch so as to define a space therewith for the uninterrupted passage of condensate, draining from the collection surface, through the trough.

References fited in the file of this patent UNITED STATES PATENTS 1,057,081 Neiman Mar. 25, 1913 1,957,292 Reeves May 1, 1934 2,427,200 Dreier Sept. 9, 1947 2,667,041 Henderson Jan. 26, 1954 

